A modelling perspective on precipitationin the Indus River Basin: from synopticto Holocene variability
type: CreativeWork
description: The Indus River civilisation was the first urban society in South Asia. Its demise, ca. 4000 years ago, might have been caused by environmental factors, such as recurrent drought conditions. Yet, palaeoclimate archives present a fragmented picture of the climate at that time. This thesis explores the potential value of global climate models to further interpret the archaeological context. Precipitation variability is investigated at various timescales due to their different impact on human societies and their importance in the climate system: the synoptic scale, the seasonal cycle, the inter-annual to multi-decadal variability, and the multi-millennial Holocene trends. The precipitation from several climate model simulations is evaluated at each of these timescales. Indus River Basin precipitation is first explored in observational datasets. This study highlights the quality of ERA5 reanalysis, which is used as a reference in the subsequent chapters. Statistical tools show that more than 80\% of the precipitation in the Upper Indus Basin is related to cross-barrier moisture transport along the Himalayan foothills. The climate models analysed (IPSL-CM6-A, MRI-ESM2-0 and GISS-E2-1-G) generally reproduce this process well, but the seasonality of cross-barrier moisture transport is biased, resulting in precipitation biases: the main wet season, the summer monsoon, is shorter and significantly dryer, while the second wet season, in winter, is longer and more active. The link between winter precipitation, cross-barrier moisture transport and Western Disturbances is further explored, first in ERA5 and then compared to IPSL-CM6-A model output. Sub-daily resolution is needed to determine the origin of the positive precipitation bias in winter. This bias is related to differences in the atmospheric circulation associated with Western Disturbances. The stronger Subtropical Westerly Jet is also key to understand the precipitation overestimation. Centennial to millennial-scale p…
abstract: The Indus River civilisation was the first urban society in South Asia. Its demise, ca. 4000 years ago, might have been caused by environmental factors, such as recurrent drought conditions. Yet, palaeoclimate archives present a fragmented picture of the climate at that time. This thesis explores the potential value of global climate models to further interpret the archaeological context. Precipitation variability is investigated at various timescales due to their different impact on human societies and their importance in the climate system: the synoptic scale, the seasonal cycle, the inter-annual to multi-decadal variability, and the multi-millennial Holocene trends. The precipitation from several climate model simulations is evaluated at each of these timescales. Indus River Basin precipitation is first explored in observational datasets. This study highlights the quality of ERA5 reanalysis, which is used as a reference in the subsequent chapters. Statistical tools show that more than 80\% of the precipitation in the Upper Indus Basin is related to cross-barrier moisture transport along the Himalayan foothills. The climate models analysed (IPSL-CM6-A, MRI-ESM2-0 and GISS-E2-1-G) generally reproduce this process well, but the seasonality of cross-barrier moisture transport is biased, resulting in precipitation biases: the main wet season, the summer monsoon, is shorter and significantly dryer, while the second wet season, in winter, is longer and more active. The link between winter precipitation, cross-barrier moisture transport and Western Disturbances is further explored, first in ERA5 and then compared to IPSL-CM6-A model output. Sub-daily resolution is needed to determine the origin of the positive precipitation bias in winter. This bias is related to differences in the atmospheric circulation associated with Western Disturbances. The stronger Subtropical Westerly Jet is also key to understand the precipitation overestimation. Centennial to millennial-scale p…
author: Baudouin, Jean-Philippe
language: eng
keywords: climate, meteorology, paleoclimate, precipitation, Indus civilization, Indus River, Monsoon
license: https://www.repository.cam.ac.uk/bitstreams/8ef6a05a-aa2c-48ec-a447-9aae2d59006b/download
license: https://creativecommons.org/licenses/by/4.0/
date published: 2020-09-01
date modified: 2026-07-24T01:33:30Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.68377